1-Ethoxy-1,1,2,2,3,3,4,4,4,-nonafluorobutane refrigerant compositions comprising a fluoroether and uses thereof

ABSTRACT

Disclosed here in are refrigerant or heat transfer fluid compositions comprising C 4 F 9 OC 2 H 5  compositions and at least one hydrofluoroether, which are useful in refrigerain or air conditioning apparatus or as heat transfer fluids. The compositions of the present invention are also useful in centrifugal compressor apparatus that employ two-stage compressors or single slab single pass heat exchangers.

CROSS REFERENCE(S) TO RELATED APPLICATION(S)

This application claims the priority benefit of U.S. ProvisionalApplication 60/536,819, filed Jan. 14, 2004, and U.S. ProvisionalApplication 60/537,453, filed Jan. 15, 2004, and U.S. ProvisionalApplication 60/549,978, filed Mar. 4, 2004, and U.S. ProvisionalApplication 60/575,037, filed May 26, 2004, and U.S. ProvisionalApplication 60/584,785, filed Jun. 29, 2004.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to compositions suitable for use inrefrigeration and air conditioning apparatus comprising at least onehydrofluoroether. Further, the present invention relates to compositionssuitable for use in refrigeration and air-conditioning apparatusemploying a centrifugal compressor comprising at least onehydrofluoroether. The compositions of the present invention may beazeotropic or near azeotropic in nature and are useful in processes forproducing refrigeration or heat or as heat transfer fluids.

2. Description of Related Art

The refrigeration industry has been working for the past few decades tofind replacement refrigerants for the ozone depletingchlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) beingphased out as a result of the Montreal Protocol. The solution for mostrefrigerant producers has been the commercialization ofhydrofluorocarbon (HFC) refrigerants. The new HFC refrigerants, HFC-134abeing the most widely used at this time, have zero ozone depletionpotential and thus are not affected by the current regulatory phase outas a result of the Montreal Protocol.

Further environmental regulations may ultimately cause global phase outof certain HFC refrigerants. Currently, the automobile industry isfacing regulations relating to global warming potential for refrigerantsused in mobile air-conditioning. Therefore, there is a great currentneed to identify new refrigerants with reduced global warming potentialfor the automobile air-conditioning market. Should the regulations bemore broadly applied in the future, an even greater need will be feltfor refrigerants that can be used in all areas of the refrigeration andair-conditioning industry.

Currently proposed replacement refrigerants for HFC-134a includeHFC-152a, pure hydrocarbons such as butane or propane, or “natural”refrigerants such as CO₂ or ammonia. Many of these suggestedreplacements are toxic, flammable, and/or have low energy efficiency.Therefore, new alternatives are constantly being sought.

The object of the present invention is to provide novel refrigerantcompositions and heat transfer fluids that provide uniquecharacteristics to meet the demands of low or zero ozone depletionpotential and lower global warming potential as compared to currentrefrigerants.

BRIEF SUMMARY OF THE INVENTION The present invention relates torefrigerant and heat transfer fluid compositions selected from the groupconsisting of:

-   -   C₄F₉OC₂H₅ and 1-(difluoromethoxy)-1,2,2-trifluoroethane;    -   C₄F₉OC₂H₅ and 1-difluoromethoxy-2,2-difluoroethane;    -   C₄F₉OC₂H₅ and 2-methoxy-1,1,2-trifluoroethane;    -   C₄F₉OC₂H₅ and 1,1-difluoro-2-methoxyethane; and    -   C₄F₉OC₂H₅ and 1-(1,1,2,2-tetrafluoroethoxy)propane.

The present invention further relates to the above listed compositionsspecifically suitable for use in refrigeration or air conditioningapparatus employing a centrifugal compressor.

The present invention further relates to the above listed compositionsspecifically suitable for use in refrigeration or air conditioningapparatus employing a multi-stage, preferably two-stage centrifugalcompressor.

The present invention further relates to the above listed compositionsspecifically suitable for use in refrigeration or air conditioningapparatus employing a single pass/single slab heat exchanger.

The present invention further relates to azeotropic or near azeotropicrefrigerant compositions. These compositions are useful in refrigerationor air conditioning apparatus. The compositions are also useful inrefrigeration or air conditioning apparatus employing a centrifugalcompressor.

The present invention further relates to processes for producingrefrigeration, heat, and transfer of heat from a heat source to a heatsink using the present inventive compositions.

DETAILED DESCRIPTION OF THE INVENTION

Disclosed here are compositions comprising C₄F₉OC₂H₅ and at least onefluoroether.

The hydrofluorocarbons of the present invention comprise compoundscontaining hydrogen, fluorine and carbon. These hydrofluorocarbons maybe represented by the formula C_(x)H_(2x+2−y)F_(y). In the formula, xmay equal 3 to 8 and y may equal 1-17. The hydrofluorocarbons may bestraight chain, branched chain or cyclic compounds having from about 3to 8 carbon atoms. Preferred hydrofluorocarbons have 3 to 6 carbon atomsand no more than 5 fluorine atoms. Representative hydrofluorocarbons arelisted in Table 1. TABLE 1 CAS Reg. Compound Chemical Formula ChemicalName No. Hydrofluoroethers HFOC-236caE CHF₂OCF₂CHF₂1-difluoromethoxy-1,1,2,2- 32778-11-3 tetrafluoroethane HFOC-236eaEβγCHF₂OCHFCF₃ 2-difluoromethoxy-1,1,1,2- 57041-67-5 tetrafluoroethaneHFOC-245caEαβ CHF₂OCF₂CH₂F 1-(difluoromethoxy)-1,1,2- 69948-24-9trifluoroethane HFOC-245cbEβγ CF₃CF₂OCH₃1,1,1,2,2-pentafluoro-2-methoxyethane 22410-44-2 HFOC-245eaECHF₂OCHFCHF₂ 1-(difluoromethoxy)-1,2,2- 60113-74-8 trifluoroethaneHFOC-245ebEβγ CF₃CHFOCH₂F 2-fluoromethoxy-1,1,1,2- 56885-27-9tetrafluoroethane HFOC-245faEαβ CHF₂CH₂OCF₃1,1-difluoro-2-trifluoromethoxyethane HFOC-245faEβγ CF₃CH₂OCHF₂2-difluoromethoxy-1,1,1-trifluoroethane  1885-48-9 HFOC-254cbEβγCHF₂CF₂OCH₃ 1-methoxy-1,1,2,2-tetrafluoroethane  425-88-7 HFOC-254ebEβγCF₃CHFOCH₃ 2-methoxy-1,1,1,2-tetrafluoroethane 148380-63-6  HFOC-254faECHF₂OCH₂CHF₂ 1-difluoromethoxy-2,2-difluoroethane 32778-16-8HFOC-263ebEβγ CH₃OCHFCHF₂ 2-methoxy-1,1,2-trifluoroethane 56281-91-5HFOC-263fbEβγ CF₃CH₂OCH₃ 2-methoxy-1,1,1-trifluoroethane HFOC-272fbEβγCH₃OCH₂CHF₂ 1,1-difluoro-2-methoxyethane  461-57-4 HFOC-338mcfEβγCF₃CF₂OCH₂CF₃ 1,1,1,2,2-pentafluoro-2-(2,2,2- 156053-88-2 trifluoroethoxy)ethane HFOC-338meeEβγ CF₃CHFOCHFCF₃1,1'-oxybis(1,2,2,2-tetrafluoro)ethane 67429-44-1 HFOC-338mmzEβγ(CF₃)₂CHOCHF₂ 2-(difluoromethoxy)-1,1,1,3,3,3- 26103-08-2hexafluoropropane HFOC-338peEγδ CHF₂OCHF3-(difluoromethoxy)-1,1,1,2,2,3- 60598-11-0 hexafluoropropaneHFOC-347mccEγδ CF₃CF₂CF₂OCH₃ 1,1,1,2,2,3,3-heptafluoro-3-  375-03-1methoxypropane HFOC-347mcfEαβ CF₃OCF₂CH₂CHF₂ 1,1,3,3-tetrafluoro-1-(trifluoromethoxy)propane HFOC-347mcfEβγ CHF₂CH₂OCF₂CF₃1-(2,2-difluoroethoxy)-1,1,2,2,2- 171182-95-9  pentafluoroethaneHFOC-347mcfEγδ CHF₂OCH₂CF₂CF₃ 3-(difluoromethoxy)-1,1,1,2,2- 56860-81-2pentafluoropropane HFOC-347mfcEαβ CF₃OCH₂CF₂CHF₂ 1,1,2,2-tetrafluoro-3- 1683-81-4 (trifluoromethoxy)propane HFOC-347mmzEβγ CH₂FOCH(CF3)₂1,1,1,3,3,3-hexafluoro-2- 28523-86-6 (fluoromethoxy)propaneHFOC-347pcfEβγ CF₃CH₂OCF₂CHF₂ 1-(2,2,2-trifluoroethoxy)-1,1,2,2- 406-78-0 tetrafluoroethane HFOC-356mecE2αβγδ CH₃OCF₂CHFOCF₃1,1,2-trifluoro-1-methoxy-2-  996-56-5 (trifluoromethoxy)ethaneHFOC-356mecEγδ CH₃OCF₂CHFCF₃ 1,1,1,2,3,3-hexafluoro-3-  382-34-3methoxypropane HFOC-356mmzEβγ (CF₃)₂CHOCH₃ 1,1,1,3,3,3-hexafluoro-2-13171-18-1 methoxypropane HFOC-356pccEγδ CHF₂CF₂CF₂OCH₃1,1,2,2,3,3-hexafluoro-3- methoxypropane HFOC-356pcfEβγ CHF₂CF₂OCH₂CHF₂1-(1,1-difluoroethoxy)-1,1,2,2- tetrafluoroethane HFOC-356pcfEγδCHF₂OCH₂CF₂CHF₂ 3-(difluoromethoxy)-1,1,2,2- 35042-99-0tetrafluoropropane HFOC-365mpzEβγ CHF₂OCH(CH₃)(CF₃)2-(difluoromethoxy)-1,1,1- 327893-56-9  trifluoropropane HFOC-365mcEγδCF₃CF₂CH₂OCH₃ 1,1,1,2,2-pentafluoro-3-  378-16-5 methoxypropaneHFOC-374mefEβγ CF₃CHFOCH₂CH₃ 2-ethoxy-1,1,1,2-tetrafluoroethane50285-06-8 HFOC-374pcEβγ CH₃CH₂OCF₂CHF₂1-ethoxy-1,1,2,2-tetrafluoroethane  512-51-6 HFOC-383mEαβ CF₃OCH₂CH₂CH₃1-(trifluoromethoxy)propane 59426-77-6 HFOC-383mEβγ CH₃CH₂OCH₂CF₃1,1,1-trifluoro-2-ethoxyethane  461-24-5 HFOC-383mEγδ CF₃CH₂CH₂OCH₃1,1,1-trifluoro-3-methoxypropane  461-22-3 HFOC-383mzEαβCH₃OCH(CH₃)(CF₃) 1,1,1-trifluoro-2-methoxypropane 32793-45-6HFOC-383peEβγ CHF₂CHFOCH₂CH₃ 1-ethoxy-1,2,2-trifluoroethane 20202-98-6HFOC-42-11mccEγδ CF₃CF₂CF₂OCHFCF₃ 1,1,1,2,2,3,3-heptafluoro-3-(1,2,2,2- 3330-15-2 tetrafluoroethoxy)propane HFOC-42-11meEγδ CF₃CHFCF₂OCF₂CF₃1,1,1,2,3,3-hexafluoro-3- 142469-07-6  (pentafluoroethoxy)propaneHFOC-467mmyEβγ CH₃CH₂OCF(CF₃)₂ 2-ethoxy-1,1,1,2,3,3,3- 22137-14-0heptafluoropropane HFOC-467mccEγδ CH₃CH₂OCF₂CF₂CF₃3-ethoxy-1,1,1,2,2,3,3- 22052-86-4 heptafluoropropane HFOC-476mmzEβγCH₃CH₂OCH(CF₃)₂ 2-ethoxy-1,1,1,3,3,3-hexafluoropropane 18339-53-8HFOC-494pcEβγ CH₃CH₂CH₂OCF₂CHF₂ 1-(1,1,2,2-tetrafluoroethoxy)propane 380-48-3 HFOC-494pcEγδ CH₃CH₂OCH₂CF₂CHF₂3-ethoxy-1,1,2,2-tetrafluoropropane 24566-96-9 HFOC-494pczEβγ(CH₃)₂CHOCF₂CHF₂ 2-(1,1,2,2-tetrafluoroethoxy)propane  757-11-9HFOC-C336ceeEαβ c-OCF₂CHFCHFCF₂- 2,2,3,4,5,5-hexafluorotetrahydrofuran24280-80-6 HFOC-C345mzeEαβ c-OCHFCHFCH(CF₃)-2,3-difluoro-4-(trifluoromethyl)oxetane 74985-21-0

The compounds listed in Table 1 are available commercially or may beprepared by processes known in the art or as described below. C₄F₉OC₂H₅is a mixture of isomers and is available commercially from 3M™ (St.Paul, Minn.).

Compositions of the present invention have no ozone depletion potentialand low global warming potential. For example, fluoroethers, alone or inmixtures will have global warming potentials lower than many HFCrefrigerants currently in use. The refrigerant or heat transfercompositions are selected from the group consisting of:

-   -   C₄F₉OC₂H₅ and 1-(difluoromethoxy)-1,2,2-trifluoroethane;    -   C₄F₉OC₂H₅ and 1-difluoromethoxy-2,2-difluoroethane;    -   C₄F₉OC₂H₅ and 2-methoxy-1,1,2-trifluoroethane;    -   C₄F₉OC₂H₅ and 1,1-difluoro-2-methoxyethane; and    -   C₄F₉OC₂H₅ and 1-(1,1,2,2-tetrafluoroethoxy)propane.

The refrigerant or heat transfer compositions of the present inventionmay be azeotropic or near azeotropic compositions. An azeotropiccomposition is a liquid admixture of two or more substances that has aconstant boiling point that may be above or below the boiling points ofthe individual components. As such an azeotropic composition will notfractionate within the refrigeration or air conditioning system duringoperation, which may reduce efficiency of the system. Additionally, anazeotropic composition will not fractionate upon leakage from therefrigeration or air conditioning system. In the situation where onecomponent of a mixture is flammable, fractionation during leakage couldlead to a flammable composition either within the system or outside ofthe system.

A near azeotropic composition is a substantially constant boiling,liquid admixture of two or more substances that behaves essentially as asingle substance. One way to characterize a near azeotropic compositionis that the vapor produced by partial evaporation or distillation of theliquid has substantially the same composition as the liquid from whichit was evaporated or distilled, that is, the admixture distills/refluxeswithout substantial composition change. Another way to characterize anear azeotropic composition is that the bubble point vapor pressure andthe dew point vapor pressure of the composition at a particulartemperature are substantially the same. Herein, a composition is nearazeotropic if, after 50 weight percent of the composition is removed,such as by evaporation or boiling off, the difference in vapor pressurebetween the original composition and the composition remaining after 50weight percent of the original composition has been removed is less thanabout 10 percent.

The azeotropic refrigerant compositions of the present invention arelisted in Table 2. TABLE 2 Azeotrope Concentration Azeotrope Component AComponent B Wt % A Wt % B BP (° C.) C₄F₉OC₂H₅ HFOC-245eaE 11.9 88.1 52.7C₄F₉OC₂H₅ HFOC-254faE 26.0 74.0 54.0 C₄F₉OC₂H₅ HFOC-263ebEβγ 40.2 59.854.0 C₄F₉OC₂H₅ HFOC-272fbEβγ 19.0 81.0 48.1 C₄F₉OC₂H₅ HFOC-494pcEβγ 36.363.7 71.2

The near azeotropic refrigerant compositions and concentration ranges ofthe present invention are listed in Table 3. TABLE 3 Near AzeotropicConcentration Range Compounds (A/B) wt % A/wt % B C₄F₉OC₂H₅/HFOC-245eaE1-62/99-38 C₄F₉OC₂H₅/HFOC-254faE 1-67/99-33 C₄F₉OC₂H₅/HFOC-263ebEβγ1-76/99-24 C₄F₉OC₂H₅/HFOC-272fbEβγ 1-67/99-33 C₄F₉OC₂H₅/HFOC-494pcEβγ1-99/99-1 

Additional compounds from the list in Table 1 may be added to the binarycompositions of the present invention to form ternary or higher ordercompositions.

The azeotropic or near azeotropic compositions of the present inventionmay further comprise about 0.01 weight percent to about 5 weight percentof a thermal stabilizer such as nitromethane.

The compositions of the present invention may further comprise anultra-violet (UV) dye and optionally a solubilizing agent. The UV dye isa useful component for detecting leaks of the refrigerant composition bypermitting one observe the fluorescence of the dye under an ultra-violetlight at the point of a leak within a refrigeration or air-conditioningsystem. Solubilizing agents may be needed due to poor solubility of suchUV dyes in some refrigerants.

By “ultra-violet” dye is meant a UV fluorescent composition that absorbslight in the ultra-violet or “near” ultra-violet region of theelectromagnetic spectrum. The fluorescence produced by the UVfluorescent dye under illumination by a UV light that emits radiationwith wavelength anywhere from 10 nanometer to 750 nanometer may bedetected. Therefore, if refrigerant containing such a UV fluorescent dyeis leaking from a given point in a refrigeration or air conditioningapparatus, the fluorescence can be detected at the leak point. Such UVfluorescent dyes include but are not limited to naphthalimides,perylenes, coumarins, anthracenes, phenanthracenes, xanthenes,thioxanthenes, naphthoxanthenes, fluoresceins, and derivatives orcombinations thereof.

Solubilizing agents of the present invention comprise at least onecompound selected from the group consisting of hydrocarbons, hydrocarbonethers, polyoxyalkylene glycol ethers, amides, nitriles, ketones,chlorocarbons, esters, lactones, aryl ethers, fluoroethers and1,1,1-trifluoroalkanes.

Hydrocarbon solubilizing agents of the present invention r comprisehydrocarbons including straight chained, branched chain or cyclicalkanes or alkenes containing 5 or fewer carbon atoms and only hydrogenwith no other functional groups. Representative hydrocarbon solubilizingagents comprise propane, propylene, cyclopropane, n-butane, isobutane,and n-pentane. It should be noted that if the refrigerant is ahydrocarbon, then the solubilizing agent may not be the samehydrocarbon.

Hydrocarbon ether solubilizing agents of the present invention compriseethers containing only carbon, hydrogen and oxygen, such as dimethylether (DME).

Polyoxyalkylene glycol ether solubilizing agents of the presentinvention are represented by the formula R¹[(OR²)_(x)OR³]_(y), wherein:x is an integer from 1-3; y is an integer from 1-4; R¹ is selected fromhydrogen and aliphatic hydrocarbon radicals having 1 to 6 carbon atomsand y bonding sites; R² is selected from aliphatic hydrocarbyleneradicals having from 2 to 4 carbon atoms; R³ is selected from hydrogenand aliphatic and alicyclic hydrocarbon radicals having from 1 to 6carbon atoms; at least one of R¹ and R³ is said hydrocarbon radical; andwherein said polyoxyalkylene glycol ethers have a molecular weight offrom about 100 to about 300 atomic mass units. In the presentpolyoxyalkylene glycol ether solubilizing agents represented byR¹[(OR²)_(x)OR³]_(y): x is preferably 1-2; y is preferably 1; R¹ and R³are preferably independently selected from hydrogen and aliphatichydrocarbon radicals having 1 to 4 carbon atoms; R² is preferablyselected from aliphatic hydrocarbylene radicals having from 2 or 3carbon atoms, most preferably 3 carbon atoms; the polyoxyalkylene glycolether molecular weight is preferably from about 100 to about 250 atomicmass units, most preferably from about 125 to about 250 atomic massunits. The R¹ and R³ hydrocarbon radicals having 1 to 6 carbon atoms maybe linear, branched or cyclic. Representative R¹ and R³ hydrocarbonradicals include methyl, ethyl, propyl, isopropyl, butyl, isobutyl,sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl, tert-pentyl,cyclopentyl, and cyclohexyl. Where free hydroxyl radicals on the presentpolyoxyalkylene glycol ether solubilizing agents may be incompatiblewith certain compression refrigeration apparatus materials ofconstruction (e.g. Mylar®), R¹ and R³ are preferably aliphatichydrocarbon radicals having 1 to 4 carbon atoms, most preferably 1carbon atom. The R² aliphatic hydrocarbylene radicals having from 2 to 4carbon atoms form repeating oxyalkylene radicals—(OR²)_(x)—that includeoxyethylene radicals, oxypropylene radicals, and oxybutylene radicals.The oxyalkylene radical comprising R² in one polyoxyalkylene glycolether solubilizing agent molecule may be the same, or one molecule maycontain different R² oxyalkylene groups. The present polyoxyalkyleneglycol ether solubilizing agents preferably comprise at least oneoxypropylene radical. Where R¹ is an aliphatic or alicyclic hydrocarbonradical having 1 to 6 carbon atoms and y bonding sites, the radical maybe linear, branched or cyclic. Representative R¹ aliphatic hydrocarbonradicals having two bonding sites include, for example, an ethyleneradical, a propylene radical, a butylene radical, a pentylene radical, ahexylene radical, a cyclopentylene radical and a cyclohexylene radical.Representative R¹ aliphatic hydrocarbon radicals having three or fourbonding sites include residues derived from polyalcohols, such astrimethylolpropane, glycerin, pentaerythritol,1,2,3-trihydroxycyclohexane and 1,3,5-trihydroxycyclohexane, by removingtheir hydroxyl radicals.

Representative polyoxyalkylene glycol ether solubilizing agents includebut are not limited to: CH₃OCH₂CH(CH₃)O(H or CH₃) (propylene glycolmethyl (or dimethyl) ether), CH₃O[CH₂CH(CH₃)O]₂(H or CH₃) (dipropyleneglycol methyl (or dimethyl) ether), CH₃O[CH₂CH(CH₃)O]₃(H or CH₃)(tripropylene glycol methyl (or dimethyl) ether), C₂H₅OCH₂CH(CH₃)O(H orC₂H₅) (propylene glycol ethyl (or diethyl) ether), C₂H₅O[CH₂CH(CH₃)O]₂(Hor C₂H₅) (dipropylene glycol ethyl (or diethyl) ether),C₂H₅O[CH₂CH(CH₃)O]₃(H or C₂H₅) (tripropylene glycol ethyl (or diethyl)ether), C₃H₇OCH₂CH(CH₃)O(H or C₃H₇) (propylene glycol n-propyl (ordi-n-propyl) ether), C₃H₇O[CH₂CH(CH₃)O]₂(H or C₃H₇) (dipropylene glycoln-propyl (or di-n-propyl) ether), C₃H₇O[CH₂CH(CH₃)O]₃(H or C₃H₇)(tripropylene glycol n-propyl (or di-n-propyl) ether), C₄H₉OCH₂CH(CH₃)OH(propylene glycol n-butyl ether), C₄H₉O[CH₂CH(CH₃)O]₂(H or C₄H₉)(dipropylene glycol n-butyl (or di-n-butyl) ether),C₄H₉O[CH₂CH(CH₃)O]₃(H or C₄H₉) (tripropylene glycol n-butyl (ordi-n-butyl) ether), (CH₃)₃COCH₂CH(CH₃)OH (propylene glycol t-butylether), (CH₃)₃CO[CH₂CH(CH₃)O]₂(H or (CH₃)₃) (dipropylene glycol t-butyl(or di-t-butyl) ether), (CH₃)₃CO[CH₂CH(CH₃)O]₃(H or (CH₃)₃)(tripropylene glycol t-butyl (or di-t-butyl) ether), C₅H₁₁OCH₂CH(CH₃)OH(propylene glycol n-pentyl ether), C₄H₉OCH₂CH(C₂H₅)OH (butylene glycoln-butyl ether), C₄H₉o[CH₂CH(C₂H₅)O]₂H (dibutylene glycol n-butyl ether),trimethylolpropane tri-n-butyl ether (C₂H₅C(CH₂O(CH₂)₃CH₃)₃) andtrimethylolpropane di-n-butyl ether (C₂H₅C(CH₂OC(CH₂)₃CH₃)₂CH₂OH).

Amide solubilizing agents of the present invention comprise thoserepresented by the formulae R¹CONR²R³ and cyclo-[R⁴CON(R⁵)—], whereinR¹, R², R³ and R⁵ are independently selected from aliphatic andalicyclic hydrocarbon radicals having from 1 to 12 carbon atoms; R⁴ isselected from aliphatic hydrocarbylene radicals having from 3 to 12carbon atoms; and wherein said amides have a molecular weight of fromabout 100 to about 300 atomic mass units. The molecular weight of saidamides is preferably from about 160 to about 250 atomic mass units. R¹,R², R³ and R⁵ may optionally include substituted hydrocarbon radicals,that is, radicals containing non-hydrocarbon substituents selected fromhalogens (e.g., fluorine, chlorine) and alkoxides (e.g. methoxy). R¹,R², R³ and R⁵ may optionally include heteroatom-substituted hydrocarbonradicals, that is, radicals, which contain the atoms nitrogen (aza-),oxygen (oxa-) or sulfur (thia-) in a radical chain otherwise composed ofcarbon atoms. In general, no more than three non-hydrocarbonsubstituents and heteroatoms, and preferably no more than one, will bepresent for each 10 carbon atoms in R¹⁻³, and the presence of any suchnon-hydrocarbon substituents and heteroatoms must be considered inapplying the aforementioned molecular weight limitations. Preferredamide solubilizing agents consist of carbon, hydrogen, nitrogen andoxygen. Representative R¹, R², R³ and R⁵aliphatic and alicyclichydrocarbon radicals include methyl, ethyl, propyl, isopropyl, butyl,isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl,tert-pentyl, cyclopentyl, cyclohexyl, heptyl, octyl, nonyl, decyl,undecyl, dodecyl and their configurational isomers. A preferredembodiment of amide solubilizing agents are those wherein R⁴ in theaforementioned formula cyclo-[R⁴CON(R⁵)—] may be represented by thehydrocarbylene radical (CR⁶R⁷)_(n), in other words, the formula:cyclo-[(CR⁶R⁷)_(n)CON(R⁵)—] wherein: the previously-stated values formolecular weight apply; n is an integer from 3 to 5; R⁵ is a saturatedhydrocarbon radical containing 1 to 12 carbon atoms; R⁶ and R⁷ areindependently selected (for each n) by the rules previously offereddefining R¹⁻³. In the lactams represented by the formula:cyclo-[(CR⁶R⁷)_(n)CON(R⁵)—], all R⁶ and R⁷ are preferably hydrogen, orcontain a single saturated hydrocarbon radical among the n methyleneunits, and R⁵ is a saturated hydrocarbon radical containing 3 to 12carbon atoms. For example, 1-(saturated hydrocarbonradical)-5-methylpyrrolidin-2-ones.

Representative amide solubilizing agents include but are not limited to:1-octylpyrrolidin-2-one, 1-decylpyrrolidin-2-one,1-octyl-5-methylpyrrolidin-2-one, 1-butylcaprolactam,1-cyclohexylpyrrolidin-2-one, 1-butyl-5-methylpiperid-2-one,1-pentyl-5-methylpiperid-2-one, 1-hexylcaprolactam,1-hexyl-5-methylpyrrolidin-2-one, 5-methyl-1-pentylpiperid-2-one,1,3-dimethylpiperid-2-one, 1-methylcaprolactam,1-butyl-pyrrolidin-2-one, 1,5-dimethylpiperid-2-one,1-decyl-5-methylpyrrolidin-2-one, 1-dodecylpyrrolid-2-one,N,N-dibutylformamide and N,N-diisopropylacetamide.

Ketone solubilizing agents of the present invention comprise ketonesrepresented by the formula R¹COR², wherein R¹ and R² are independentlyselected from aliphatic, alicyclic and aryl hydrocarbon radicals havingfrom 1 to 12 carbon atoms, and wherein said ketones have a molecularweight of from about 70 to about 300 atomic mass units. R¹ and R² insaid ketones are preferably independently selected from aliphatic andalicyclic hydrocarbon radicals having 1 to 9 carbon atoms. The molecularweight of said ketones is preferably from about 100 to 200 atomic massunits. R¹ and R² may together form a hydrocarbylene radical connectedand forming a five, six, or seven-membered ring cyclic ketone, forexample, cyclopentanone, cyclohexanone, and cycloheptanone. R¹ and R²may optionally include substituted hydrocarbon radicals, that is,radicals containing non-hydrocarbon substituents selected from halogens(e.g., fluorine, chlorine) and alkoxides (e.g. methoxy). R¹ and R² mayoptionally include heteroatom-substituted hydrocarbon radicals, that is,radicals, which contain the atoms nitrogen (aza-), oxygen (keto-, oxa-)or sulfur (thia-) in a radical chain otherwise composed of carbon atoms.In general, no more than three non-hydrocarbon substituents andheteroatoms, and preferably no more than one, will be present for each10 carbon atoms in R¹ and R², and the presence of any suchnon-hydrocarbon substituents and heteroatoms must be considered inapplying the aforementioned molecular weight limitations. RepresentativeR¹ and R² aliphatic, alicyclic and aryl hydrocarbon radicals in thegeneral formula R¹COR² include methyl, ethyl, propyl, isopropyl, butyl,isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl,tert-pentyl, cyclopentyl, cyclohexyl, heptyl, octyl, nonyl, decyl,undecyl, dodecyl and their configurational isomers, as well as phenyl,benzyl, cumenyl, mesityl, tolyl, xylyl and phenethyl.

Representative ketone solubilizing agents include but are not limitedto: 2-butanone, 2-pentanone, acetophenone, butyrophenone, hexanophenone,cyclohexanone, cycloheptanone, 2-heptanone, 3-heptanone,5-methyl-2-hexanone, 2-octanone, 3-octanone, diisobutyl ketone,4-ethylcyclohexanone, 2-nonanone, 5-nonanone, 2-decanone, 4-decanone,2-decalone, 2-tridecanone, dihexyl ketone and dicyclohexyl ketone.

Nitrile solubilizing agents of the present invention comprise nitrilesrepresented by the formula R¹CN, wherein R¹ is selected from aliphatic,alicyclic or aryl hydrocarbon radicals having from 5 to 12 carbon atoms,and wherein said nitriles have a molecular weight of from about 90 toabout 200 atomic mass units. R¹ in said nitrile solubilizing agents ispreferably selected from aliphatic and alicyclic hydrocarbon radicalshaving 8 to 10 carbon atoms. The molecular weight of said nitrilesolubilizing agents is preferably from about 120 to about 140 atomicmass units. R¹ may optionally include substituted hydrocarbon radicals,that is, radicals containing non-hydrocarbon substituents selected fromhalogens (e.g., fluorine, chlorine) and alkoxides (e.g. methoxy). R¹ mayoptionally include heteroatom-substituted hydrocarbon radicals, that is,radicals, which contain the atoms nitrogen (aza-), oxygen (keto-, oxa-)or sulfur (thia-) in a radical chain otherwise composed of carbon atoms.In general, no more than three non-hydrocarbon substituents andheteroatoms, and preferably no more than one, will be present for each10 carbon atoms in R¹, and the presence of any such non-hydrocarbonsubstituents and heteroatoms must be considered in applying theaforementioned molecular weight limitations. Representative R¹aliphatic, alicyclic and aryl hydrocarbon radicals in the generalformula R¹CN include pentyl, isopentyl, neopentyl, tert-pentyl,cyclopentyl, cyclohexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyland their configurational isomers, as well as phenyl, benzyl, cumenyl,mesityl, tolyl, xylyl and phenethyl. Representative nitrile solubilizingagents include but are not limited to: 1-cyanopentane,2,2-dimethyl-4-cyanopentane, 1-cyanohexane, 1-cyanoheptane,1-cyanooctane, 2-cyanooctane, 1-cyanononane, 1-cyanodecane,2-cyanodecane, 1-cyanoundecane and 1-cyanododecane.

Chlorocarbon solubilizing agents of the present invention comprisechlorocarbons represented by the formula RCl_(x), wherein; x is selectedfrom the integers 1 or 2; R is selected from aliphatic and alicyclichydrocarbon radicals having 1 to 12 carbon atoms; and wherein saidchlorocarbons have a molecular weight of from about 100 to about 200atomic mass units. The molecular weight of said chlorocarbonsolubilizing agents is preferably from about 120 to 150 atomic massunits. Representative R aliphatic and alicyclic hydrocarbon radicals inthe general formula RCl_(x) include methyl, ethyl, propyl, isopropyl,butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl,tert-pentyl, cyclopentyl, cyclohexyl, heptyl, octyl, nonyl, decyl,undecyl, dodecyl and their configurational isomers.

Representative chlorocarbon solubilizing agents include but are notlimited to: 3-(chloromethyl)pentane, 3-chloro-3-methylpentane,1-chlorohexane, 1,6-dichlorohexane, 1-chloroheptane, 1-chlorooctane,1-chlorononane, 1-chlorodecane, and 1,1,1-trichlorodecane.

Ester solubilizing agents of the present invention comprise estersrepresented by the general formula R¹CO₂R², wherein R¹ and R² areindependently selected from linear and cyclic, saturated andunsaturated, alkyl and aryl radicals. Preferred esters consistessentially of the elements C, H and O, have a molecular weight of fromabout 80 to about 550 atomic mass units.

Representative esters include but are not limited to:(CH₃)₂CHCH₂OOC(CH₂)₂₋₄OCOCH₂CH(CH₃)₂ (diisobutyl dibasic ester), ethylhexanoate, ethyl heptanoate, n-butyl propionate, n-propyl propionate,ethyl benzoate, di-n-propyl phthalate, benzoic acid ethoxyethyl ester,dipropyl carbonate, “Exxate 700” (a commercial C₇ alkyl acetate),“Exxate 800” (a commercial C₈ alkyl acetate), dibutyl phthalate, andtert-butyl acetate.

Lactone solubilizing agents of the present invention comprise lactonesrepresented by structures [A], [B], and [C]:

These lactones contain the functional group —CO₂— in a ring of six (A),or preferably five atoms (B), wherein for structures [A] and [B], R₁through R₈ are independently selected from hydrogen or linear, branched,cyclic, bicyclic, saturated and unsaturated hydrocarbyl radicals. EachR₁ though R₈ may be connected forming a ring with another R₁ through R₈.The lactone may have an exocyclic alkylidene group as in structure [C],wherein R₁ through R₆ are independently selected from hydrogen orlinear, branched, cyclic, bicyclic, saturated and unsaturatedhydrocarbyl radicals. Each R₁ though R₆ may be connected forming a ringwith another R₁ through R₆. The lactone solubilizing agents have amolecular weight range of from about 80 to about 300 atomic mass units,preferred from about 80 to about 200 atomic mass units.

Representative lactone solubilizing agents include but are not limitedto the compounds listed in Table 4. TABLE 4 Molecular Molecular AdditiveMolecular Structure Formula Weight (amu) (E,Z)-3-ethylidene-5-methyl-dihydro-furan-2-one

C₇H₁₀O₂ 126 (E,Z)-3-propylidene-5-methyl- dihydro-furan-2-one

C₈H₁₂O₂ 140 (E,Z)-3-butylidene-5-methyl- dihydro-furan-2-one

C₉H₁₄O₂ 154 (E,Z)-3-pentylidene-5-methyl- dihydro-furan-2-one

C₁₀H₁₆O₂ 168 (E,Z)-3-Hexylidene-5-methyl- dihydro-furan-2-one

C₁₁H₁₈O₂ 182 (E,Z)-3-Heptylidene-5-methyl- dihydro-furan-2-one

C₁₂H₂₀O₂ 196 (E,Z)-3-octylidene-5-methyl- dihydro-furan-2-one

C₁₃H₂₂O₂ 210 (E,Z)-3-nonylidene-5-methyl- dihydro-furan-2-one

C₁₄H₂₄O₂ 224 (E,Z)-3-decylidene-5-methyl- dihydro-furan-2-one

C₁₅H₂₆O₂ 238 (E,Z)-3-(3,5,5-trimethylhexylidene)-5-methyl-dihydrofuran-2-one

C₁₄H₂₄O₂ 224 (E,Z)-3-cyclohexylmethylidene-5- methyl-dihydrofuran-2-one

C₁₂H₁₈O₂ 194 gamma-octalactone

C₈H₁₄O₂ 142 gamma-nonalactone

C₉H₁₆O₂ 156 gamma-decalactone

C₁₀H₁₈O₂ 170 gamma-undecalactone

C₁₁H₂₀O₂ 184 gamma-dodecalactone

C₁₂H₂₂O₂ 198 3-hexyldihydro-furan-2-one

C₁₀H₁₈O₂ 170 3-heptyldihydro-furan-2-one

C₁₁H₂₀O₂ 184 cis-3-ethyl-5-methyl-dihydro-furan- 2-one

C₇H₁₂O₂ 128 cis-(3-propyl-5-methyl)-dihydro- furan-2-one

C₈H₁₄O₂ 142 cis-(3-butyl-5-methyl)-dihydro- furan-2-one

C₉H₁₆O₂ 156 cis-(3-pentyl-5-methyl)-dihydro- furan-2-one

C₁₀H₁₈O₂ 170 cis-3-hexyl-5-methyl-dihydro-furan- 2-one

C₁₁H₂₀O₂ 184 cis-3-heptyl-5-methyl-dihydro- furan-2-one

C₁₂H₂₂O₂ 198 cis-3-octyl-5-methyl-dihydro-furan- 2-one

C₁₃H₂₄O₂ 212 cis-3-(3,5,5-trimethylhexyl)-5- methyl-dihydro-furan-2-one

C₁₄H₂₆O₂ 226 cis-3-cyclohexylmethyl-5-methyl- dihydro-furan-2-one

C₁₂H₂₀O₂ 196 5-methyl-5-hexyl-dihydro-furan-2-one

C₁₁H₂₀O₂ 184 5-methyl-5-octyl-dihydro-furan-2-one

C₁₃H₂₄O₂ 212 Hexahydro-isobenzofuran-1-one

C₈H₁₂O₂ 140 delta-decalactone

C₁₀H₁₈O₂ 170 delta-undecalactone

C₁₁H₂₂O₂ 184 delta-dodecalactone

C₁₂H₂₂O₂ 198 mixture of 4-hexyl-dihydrofuran-2- one and3-hexyl-dihydro-furan-2-one

C₁₀H₁₈O₂ 170

Lactone solubilizing agents may be available commercially or prepared bymethods as described in U.S. provisional patent application Ser. No.10/910,495 (inventors being P. J. Fagan and C. J. Brandenburg), filedAug. 3, 2004, incorporated herein by reference.

Aryl ether solubilizing agents of the present invention further comprisearyl ethers represented by the formula R¹OR², wherein: R¹ is selectedfrom aryl hydrocarbon radicals having from 6 to 12 carbon atoms; R² isselected from aliphatic hydrocarbon radicals having from 1 to 4 carbonatoms; and wherein said aryl ethers have a molecular weight of fromabout 100 to about 150 atomic mass units. Representative R¹ arylradicals in the general formula R¹OR² include phenyl, biphenyl, cumenyl,mesityl, tolyl, xylyl, naphthyl and pyridyl. Representative R² aliphatichydrocarbon radicals in the general formula R¹OR² include methyl, ethyl,propyl, isopropyl, butyl, isobutyl, sec-butyl and tert-butyl.Representative aromatic ether solubilizing agents include but are notlimited to: methyl phenyl ether (anisole), 1,3-dimethyoxybenzene, ethylphenyl ether and butyl phenyl ether.

Fluoroether solubilizing agents of the present invention comprise thoserepresented by the general formula R¹OCF₂CF₂H, wherein R¹ is selectedfrom aliphatic and alicyclic hydrocarbon radicals having from about 5 toabout 15 carbon atoms, preferably primary, linear, saturated, alkylradicals. Representative fluoroether solubilizing agents include but arenot limited to: C₈H₁₇OCF₂CF₂H and C₆H₁₃OCF₂CF₂H. It should be noted thatif the refrigerant is a fluoroether, then the solubilizing agent may notbe the same fluoroether.

1,1,1-Trifluoroalkane solubilizing agents of the present inventioncomprise 1,1,1-trifluoroalkanes represented by the general formulaCF₃R¹, wherein R¹ is selected from aliphatic and alicyclic hydrocarbonradicals having from about 5 to about 15 carbon atoms, preferablyprimary, linear, saturated, alkyl radicals. Representative1,1,1-trifluoroalkane solubilizing agents include but are not limitedto: 1,1,1-trifluorohexane and 1,1,1-trifluorododecane.

Solubilizing agents of the present invention may be present as a singlecompound, or may be present as a mixture of more than one solubilizingagent. Mixtures of solubilizing agents may contain two solubilizingagents from the same class of compounds, say two lactones, or twosolubilizing agents from two different classes, such as a lactone and apolyoxyalkylene glycol ether.

In the present compositions comprising refrigerant and UV fluorescentdye, from about 0.001 weight percent to about 1.0 weight percent of thecomposition is UV dye, preferably from about 0.005 weight percent toabout 0.5 weight percent, and most preferably from 0.01 weight percentto about 0.25 weight percent.

Solubility of these UV fluorescent dyes in refrigerants may be poor.Therefore, methods for introducing these dyes into the refrigeration orair conditioning apparatus have been awkward, costly and time consuming.US patent no. RE 36,951 describes a method, which utilizes a dye powder,solid pellet or slurry of dye that may be inserted into a component ofthe refrigeration or air conditioning apparatus. As refrigerant andlubricant are circulated through the apparatus, the dye is dissolved ordispersed and carried throughout the apparatus. Numerous other methodsfor introducing dye into a refrigeration or air conditioning apparatusare described in the literature.

Ideally, the UV fluorescent dye could be dissolved in the refrigerantitself thereby not requiring any specialized method for introduction tothe refrigeration or air conditioning apparatus. The present inventionrelates to compositions including UV fluorescent dye, which may beintroduced into the system directly in the refrigerant. The inventivecompositions will allow the storage and transport of dye-containingrefrigerant even at low temperatures while maintaining the dye insolution.

In the present compositions comprising refrigerant, UV fluorescent dyeand solubilizing agent, from about 1 to about 50 weight percent,preferably from about 2 to about 25 weight percent, and most preferablyfrom about 5 to about 15 weight percent of the combined composition issolubilizing agent in the refrigerant. In the compositions of thepresent invention the UV fluorescent dye is present in a concentrationfrom about 0.001 weight percent to about 1.0 weight percent in therefrigerant, preferably from 0.005 weight percent to about 0.5 weightpercent, and most preferably from 0.01 weight percent to about 0.25weight percent.

Optionally, commonly used refrigeration system additives may optionallybe added, as desired, to compositions of the present invention in orderto enhance performance and system stability. These additives are knownwithin the field of refrigeration, and include, but are not limited to,anti wear agents, extreme pressure lubricants, corrosion and oxidationinhibitors, metal surface deactivators, free radical scavengers, andfoam control agents. In general, these additives are present in theinventive compositions in small amounts relative to the overallcomposition. Typically concentrations of from less than about 0.1 weightpercent to as much as about 3 weight percent of each additive are used.These additives are selected on the basis of the individual systemrequirements.

These additives include members of the triaryl phosphate family of EP(extreme pressure) lubricity additives, such as butylated triphenylphosphates (BTPP), or other alkylated triaryl phosphate esters, e.g.Syn-O-Ad 8478 from Akzo Chemicals, tricrecyl phosphates and relatedcompounds. Additionally, the metal dialkyl dithiophosphates (e.g. zincdialkyl dithiophosphate (or ZDDP), Lubrizol 1375 and other members ofthis family of chemicals may be used in compositions of the presentinvention. Other antiwear additives include natural product oils andasymmetrical polyhydroxyl lubrication additives, such as Synergol TMS(International Lubricants). Similarly, stabilizers such as antioxidants, free radical scavengers, and water scavengers may be employed.Compounds in this category can include, but are not limited to,butylated hydroxy toluene (BHT) and epoxides.

Solubilizing agents such as ketones may have an objectionable odor,which can be masked by addition of an odor masking agent or fragrance.Typical examples of odor masking agents or fragrances may includeEvergreen, Fresh Lemon, Cherry, Cinnamon, Peppermint, Floral or OrangePeel or sold by Intercontinental Fragrance, as well as d-limonene andpinene. Such odor masking agents may be used at concentrations of fromabout 0.001% to as much as about 15% by weight based on the combinedweight of odor masking agent and solubilizing agent.

The present invention further relates to a method of using therefrigerant or heat transfer fluid compositions further comprisingultraviolet fluorescent dye, and optionally, solubilizing agent, inrefrigeration or air conditioning apparatus. The method comprisesintroducing the refrigerant or heat transfer fluid composition into therefrigeration or air conditioning apparatus. This may be done bydissolving the UV fluorescent dye in the refrigerant or heat transferfluid composition in the presence of a solubilizing agent andintroducing the combination into the apparatus. Alternatively, this maybe done by combining solubilizing agent and and UV fluorescent dye andintroducing said combination into refrigeration or air conditioningapparatus containing refrigerant and/or heat transfer fluid. Theresulting composition is may be used in the refrigeration or airconditioning apparatus.

The present invention further relates to a method of using therefrigerant or heat transfer fluid compositions comprising ultravioletfluorescent dye to detect leaks. The presence of the dye in thecompostions allows for detection of leaking refrigerant in therefrigeration or air conditioning apparatus. Leak detection helps toaddress, resolve or prevent inefficient operation of the apparatus orsystem or equipment failure. Leak detection also helps one containchemicals used in the operation of the apparatus.

The method comprises providing the composition comprising refrigerant,ultra-violet fluorescent dye as described herein, and optionally, asolubilizing agent as described herein, to refrigeration and airconditioning apparatus and employing a sutiable means for detecting theUV fluorescent dye-containing refrigerant. Suitable means for detectingthe dye include, but are not limited to, ultra-violet lamp, oftenreferred to as a “black light” or “blue light”. Such ultra-violet lampsare commercially available from numerous sources specifically designedfor this purpose. Once the ultra-violet fluorescent dye containingcomposition has been introduced to the refrigeration or air conditioningapparatus and has been allowed to circulate throughout the system, aleak can be found by shining said ultra-violet lamp on the apparatus andobserving the fluorescence of the dye in the vicinity of any leak point.

The present invention further relates to a method of using thecompositions of the present invention for producing refrigeration orheat, wherein the method comprises producing refrigeration byevaporating said composition in the vicinity of a body to be cooled andthereafter condensing said composition; or producing heat by condensingthe said composition in the vicinity of the body to be heated andthereafter evaporating said composition.

Mechanical refrigeration is primarily an application of thermodynamicswherein a cooling medium, such as a refrigerant, goes through a cycle sothat it can be recovered for reuse. Commonly used cycles includevapor-compression, absorption, steam-jet or steam-ejector, and air.

Vapor-compression refrigeration systems include an evaporator, acompressor, a condenser, and an expansion device. A vapor-compressioncycle re-uses refrigerant in multiple steps producing a cooling effectin one step and a heating effect in a different step. The cycle can bedescribed simply as follows. Liquid refrigerant enters an evaporatorthrough an expansion device, and the liquid refrigerant boils in theevaporator at a low temperature to form a gas and produce cooling. Thelow-pressure gas enters a compressor where the gas is compressed toraise its pressure and temperature. The higher-pressure (compressed)gaseous refrigerant then enters the condenser in which the refrigerantcondenses and discharges its heat to the environment. The refrigerantreturns to the expansion device through which the liquid expands fromthe higher-pressure level in the condenser to the low-pressure level inthe evaporator, thus repeating the cycle.

There are various types of compressors that may be used in refrigerationapplications. Compressors can be generally classified as reciprocating,rotary, jet, centrifugal, scroll, screw or axial-flow, depending on themechanical means to compress the fluid, or as positive-displacement(e.g., reciprocating, scroll or screw) or dynamic (e.g., centrifugal orjet), depending on how the mechanical elements act on the fluid to becompressed.

Either positive displacement or dynamic compressors may be used in thepresent inventive process. A centrifugal type compressor is thepreferred equipment for the present refrigerant compositions.

A centrifugal compressor uses rotating elements to accelerate therefrigerant radially, and typically includes an impeller and diffuserhoused in a casing. Centrifugal compressors usually take fluid in at animpeller eye, or central inlet of a circulating impeller, and accelerateit radially outward. Some static pressure rise occurs in the impeller,but most of the pressure rise occurs in the diffuser section of thecasing, where velocity is converted to static pressure. Eachimpeller-diffuser set is a stage of the compressor. Centrifugalcompressors are built with from 1 to 12 or more stages, depending on thefinal pressure desired and the volume of refrigerant to be handled.

The pressure ratio, or compression ratio, of a compressor is the ratioof absolute discharge pressure to the absolute inlet pressure. Pressuredelivered by a centrifugal compressor is practically constant over arelatively wide range of capacities.

Positive displacement compressors draw vapor into a chamber, and thechamber decreases in volume to compress the vapor. After beingcompressed, the vapor is forced from the chamber by further decreasingthe volume of the chamber to zero or nearly zero. A positivedisplacement compressor can build up a pressure, which is limited onlyby the volumetric efficiency and the strength of the parts to withstandthe pressure.

Unlike a positive displacement compressor, a centrifugal compressordepends entirely on the centrifugal force of the high-speed impeller tocompress the vapor passing through the impeller. There is no positivedisplacement, but rather what is called dynamic-compression.

The pressure a centrifugal compressor can develop depends on the tipspeed of the impeller. Tip speed is the speed of the impeller measuredat its tip and is related to the diameter of the impeller and itsrevolutions per minute. The capacity of the centrifugal compressor isdetermined by the size of the passages through the impeller. This makesthe size of the compressor more dependent on the pressure required thanthe capacity.

Because of its high-speed operation, a centrifugal compressor isfundamentally a high volume, low-pressure machine. A centrifugalcompressor works best with a low-pressure refrigerant, such astrichlorofluoromethane (CFC-11) or 1,2,2-trichlorotrifluoroethane(CFC-113).

Large centrifugal compressors typically operate at 3000 to 7000revolutions per minute (rpm). Small turbine centrifugal compressors aredesigned for high speeds, from about 40,000 to about 70,000 (rpm), andhave small impeller sizes, typically less than 0.15 meters.

A multi-stage impeller may be used in a centrifugal compressor toimprove compressor efficiency thus requiring less power in use. For atwo-stage system, in operation, the discharge of the first stageimpeller goes to the suction intake of a second impeller. Both impellersmay operate by use of a single shaft (or axle). Each stage can build upa compression ratio of about 4 to 1; that is, the absolute dischargepressure can be four times the absolute suction pressure. An example ofa two-stage centrifugal compressor system, in this case for automotiveapplications, is described in U.S. Pat. No. 5,065,990, incorporatedherein by reference.

The compositions of the present invention suitable for use in arefrigeration or air conditioning apparatus employing a centrifugalcompressor are:

-   -   C₄F₉OC₂H₅ and 1-(difluoromethoxy)-1,2,2-trifluoroethane;    -   C₄F₉OC₂H₅ and 1-difluoromethoxy-2,2-difluoroethane;    -   C₄F₉OC₂H₅ and 2-methoxy-1,1,2-trifluoroethane;    -   C₄F₉OC₂H₅ and 1,1-difluoro-2-methoxyethane; and    -   C₄F₉OC₂H₅ and 1-(1,1,2,2-tetrafluoroethoxy)propane.        These above-listed compositions are also suitable for use in a        multi-stage centrifugal compressor, preferably for a two-stage        centrifugal compressor apparatus.

The compositions of the present invention may be used in stationaryair-conditioning, heat pumps or mobile air-conditioning andrefrigeration systems. Stationary air conditioning and heat pumpapplications include window, ductless, ducted, packaged terminal,chillers and commercial, including packaged rooftop. Refrigerationapplications include domestic or home refrigerators and freezers, icemachines, self-contained coolers and freezers, walk-in coolers andfreezers and transport refrigeration systems.

The compositions of the present invention may additionally be used inair-conditioning, heating and refrigeration systems that employ fin andtube heat exchangers, microchannel heat exchangers and vertical orhorizontal single pass tube or plate type heat exchangers.

Conventional microchannel heat exchangers may not be ideal for the lowpressure refrigerant compositions of the present invention. The lowoperating pressure and density result in high flow velocities and highfrictional losses in all components. In these cases, the evaporatordesign may be modified. Rather than several microchannel slabs connectedin series (with respect to the refrigerant path) a single slab/singlepass heat exchanger arrangement may be used. Therefore, a preferred heatexchanger for the low pressure refrigerants of the present invention isa single slab/single pass heat exchanger.

In addition to a two-stage or other multi-stage centrifugal compressorapparatus, compositions of the present invention that are suitable foruse in a refrigeration or air conditioning apparatus employing a singleslab/single pass heat exchanger are selected from the group consistingof:

-   -   C₄F₉OC₂H₅ and 1-(difluoromethoxy)-1,2,2-trifluoroethane;    -   C₄F₉OC₂H₅ and 1-difluoromethoxy-2,2-difluoroethane;    -   C₄F₉OC₂H₅ and 2-methoxy-1,1,2-trifluoroethane;    -   C₄F₉OC₂H₅ and 1,1-difluoro-2-methoxyethane; and C₄F₉OC₂H₅ and        1-(1,1,2,2-tetrafluoroethoxy)propane.

The compositions of the present invention are particularly useful insmall turbine centrifugal compressors, which can be used in auto andwindow air conditioning or heat pump as well as other applications.These high efficiency miniature centrifugal compressors may be driven byan electric motor and can therefore be operated independently of theengine speed. A constant compressor speed allows the system to provide arelatively constant cooling capacity at all engine speeds. This providesan opportunity for efficiency improvements especially at higher enginespeeds as compared to a conventional R-134a automobile air-conditioningsystem. When the cycling operation of conventional systems at highdriving speeds is taken into account, the advantage of these lowpressure systems becomes even greater.

Some of the low pressure refrigerant fluids of the present invention maybe suitable as drop-in replacements for CFC-113 in existing centrifugalequipment.

The present invention relates to a process for producing refrigerationcomprising evaporating the compositions of the present invention in thevicinity of a body to be cooled, and thereafter condensing saidcompositions.

The present invention further relates to a process for producing heatcomprising condensing the compositions of the present invention in thevicinity of a body to be heated, and thereafter evaporating saidcompositions.

The present invention further relates to a process for transfer of heatfrom a heat source to a heat sink wherein the compositions of thepresent invention serve as heat transfer fluids. Said process for heattransfer comprises transferring the compositions of the presentinvention from a heat source to a heat sink.

Heat transfer fluids are utilized to transfer, move or remove heat fromone space, location, object or body to a different space, location,object or body by radiation, conduction, or convection. A heat transferfluid may function as a secondary coolant by providing means of transferfor cooling (or heating) from a remote refrigeration (or heating)system. In some systems, the heat transfer fluid may remain in aconstant state throughout the transfer process (i.e., not evaporate orcondense). Alternatively, evaporative cooling processes may utilize heattransfer fluids as well.

A heat source may be defined as any space, location, object or body fromwhich it is desirable to transfer, move or remove heat. Examples of heatsources may be spaces (open or enclosed) requiring refrigeration orcooling, such as refrigerator or freezer cases in a supermarket,building spaces requiring air conditioning, or the passenger compartmentof an automobile requiring air conditioning. A heat sink may be definedas any space, location, object or body capable of absorbing heat. Avapor compression refrigeration system is one example of such a heatsink.

EXAMPLES Example 1 Impact of Vapor Leakage

A vessel is charged with an initial composition at a specifiedtemperature, and the initial vapor pressure of the composition ismeasured. The composition is allowed to leak from the vessel, while thetemperature is held constant, until 50 weight percent of the initialcomposition is removed, at which time the vapor pressure of thecomposition remaining in the vessel is measured. The results aresummarized in Table 4 below. TABLE 4 After 50% After 50% CompoundsInitial Initial Leak Leak wt % A/wt % B Psia kPa Psia kPa Delta P %C₄F₉OC₂H₅/HFOC-245eaE (52.7° C.) 11.9/88.1 14.67 101.15 14.67 101.150.0%  1/99 14.57 100.46 14.57 100.46 0.0%  0/100 14.55 100.32 14.55100.32 0.0% 40/60 14.21 97.98 13.89 95.77 2.3% 60/40 13.28 91.56 12.0983.36 9.0% 61/39 13.21 91.08 11.96 82.46 9.5% 62/38 13.14 90.60 11.8381.57 10.0% 100/0  6.61 45.57 6.61 45.57 0.0% C₄F₉OC₂H₅/HFOC-254faE(54.0° C.) 26.0/74.0 14.72 101.49 14.72 101.49 0.0% 10/90 14.52 100.1114.43 99.49 0.6%  1/99 14.13 97.42 14.10 97.22 0.2%  0/100 14.07 97.0114.07 97.01 0.0% 60/40 14.00 96.53 13.17 90.80 5.9% 67/33 13.58 93.6312.25 84.46 9.8% 100/0  6.93 47.78 6.93 47.78 0.0%C₄F₉OC₂H₅/HFOC-263ebEβγ (54.0° C.) 40.2/59.8 14.71 101.42 14.71 101.420.0% 20/80 14.48 99.84 14.37 99.08 0.8% 10/90 14.19 97.84 14.06 96.940.9%  1/99 13.81 95.22 13.79 95.08 0.1%  0/100 13.76 94.87 13.76 94.870.0% 60/40 14.49 99.91 14.25 98.25 1.7% 75/25 13.90 95.84 12.73 87.778.4% 76/24 13.84 95.42 12.53 86.39 9.5% 100/0  6.93 47.78 6.93 47.780.0% C₄F₉OC₂H₅/HFOC-272fbEβγ (48.1° C.) 19.0/81.0 14.70 101.35 14.70101.35 0.0% 10/90 14.66 101.08 14.65 101.01 0.1%  1/99 14.52 100.1114.52 100.11 0.0%  0/100 14.50 99.97 14.50 99.97 0.0% 40/60 14.51 100.0414.36 99.01 1.0% 60/40 13.91 95.91 13.08 90.18 6.0% 67/33 13.52 93.2212.17 83.91 10.0% 100/0  5.57 38.40 5.57 38.40 0.0%C₄F₉OC₂H₅/HFOC-494pcEβγ (71.2° C.) 36.3/63.7 14.72 101.49 14.72 101.490.0% 20/80 14.64 100.94 14.62 100.80 0.1% 10/90 14.51 100.04 14.49 99.910.1%  1/99 14.35 98.94 14.34 98.87 0.1%  0/100 14.33 98.80 14.33 98.800.0% 60/40 14.52 100.11 14.47 99.77 0.3% 80/20 13.91 95.91 13.77 94.941.0% 90/10 13.37 92.18 13.23 91.22 1.0% 99/1  12.67 87.36 12.65 87.220.2% 100/0  12.58 86.74 12.58 86.74 0.0%

The results show the difference in vapor pressure between the originalcomposition and the composition remaining after 50 weight percent hasbeen removed is less then about 10 percent for compositions of thepresent invention. This indicates compositions of the present inventionare azeotropic or near-azeotropic. Where an azeotrope is present, thedata show compositions of the present invention have an initial vaporpressure higher than the vapor pressure of either pure component.

EXAMPLE 2 Tip Speed to Develop Pressure

Tip speed can be estimated by making some fundamental relationships forrefrigeration equipment that use centrifugal compressors. The torque animpeller ideally imparts to a gas is defined asT=m*(v _(2*) r ₂ −y ₁ *r ₁)  Equation 1where

-   -   T torque, N*m    -   m=mass rate of flow, kg/s    -   v₂=tangential velocity of refrigerant leaving impeller (tip        speed), m/s    -   r₂=radius of exit impeller, m    -   v₁=tangential velocity of refrigerant entering impeller, m/s    -   r₁=radius of inlet of impeller, m

Assuming the refrigerant enters the impeller in an essentially radialdirection, the tangential component of the velocity v1=0, thereforeT=m*v _(2*) r ₂  Equation 2

The power required at the shaft is the product of the torque and therotative speedP=T*w  Equation 3where

-   -   P=power, W    -   w=rotative speed, rez/s        therefore,        P=T*w=m*v _(2*) r _(2*) w  Equation 4

At low refrigerant flow rates, the tip speed of the impeller and thetangential velocity of the refrigerant are nearly identical; thereforer _(2*) w=v ₂  Equation 5andP=m*v _(2*) v ₂  Equation 6

Another expression for ideal power is the product of the mass rate offlow and the isentropic work of compression,P=m*H _(i)*(1000 J/kJ)  Equation 7where

-   -   H_(i)=Difference in enthalpy of the refrigerant from a saturated        vapor at the evaporating conditions to saturated condensing        conditions, kJ/kg.

Combining the two expressions Equation 6 and 7 produces,v _(2*) v ₂=1000*H _(i)  Equation 8

Although Equation 8 is based on some fundamental assumptions, itprovides a good estimate of the tip speed of the impeller and providesan important way to compare tip speeds of refrigerants.

Table 6 below shows theoretical tip speeds that are calculated for1,2,2-trichlorotrifluoroethane (CFC-113) and compositions of the presentinvention. The conditions assumed for this comparison are: Evaporatortemperature  40.0° F. (4.4° C.) Condenser temperature 110.0° F. (43.3°C.) Liquid subcool temperature  10.0° F. (5.5° C.) Return gastemperature  75.0° F. (23.8° C.) Compressor efficiency is 70%

These are typical conditions under which small turbine centrifugalcompressors perform. TABLE 6 V2 rel Refrigerant C₄F₉OC₂H₅ Hi Hi*0.7Hi*0.7 V2 to CFC- composition wt % wt % B Btu/lb Btu/lb KJ/Kg m/s 113CFC-113 10.92 7.6 17.8 133.3 n/a C₄F₉OC₂H₅ plus (B): HFOC-245eaE 11.988.1 12.57 8.8 20.5 143.1 107% HFOC-254faE 26.0 74.0 13.75 9.6 22.4149.6 112% HFOC-263ebEβγ 40.2 59.8 14.45 10.1 23.5 153.4 115%HFOC-272fbEβγ 19.0 81.0 16.41 11.5 26.7 163.5 123% HFOC-494pcEβγ 36.363.7 15.65 11.0 25.5 159.6 120%

The Example shows that compounds of the present invention have tipspeeds within about +/−30 percent of CFC-113 and would be effectivereplacements for CFC-113 with minimal compressor design changes. Mostpreferred compositions have tip speeds within about +/−15 percent ofCFC-113.

EXAMPLE 3 Performance Data

Table 7 shows the performance of various refrigerants compared toCFC-113. The data are based on the following conditions. Evaporatortemperature  40.0° F. (4.4° C.) Condenser temperature 110.0° F. (43.3°C.) Subcool temperature  10.0° F. (5.5° C.) Return gas temperature 75.0° F. (23.8° C.) Compressor efficiency is 70%

TABLE 7 Compr Compr Evap Evap Cond Cond Disch Disch Refrigerant wt % wt% Pres Pres Pres Pres Temp Temp Capacity Capacity Composition C₄F₉OC₂H₅B (Psia) (kPa) (Psia) (kPa) (F.) (C.) COP (Btu/min) (kW) CFC-113 2.7 1912.8 88 156.3 69.1 4.18 14.8 0.26 C₄F₉OC₂H₅ plus (B): HFOC-245eaE 11.988.1 2.2 15 11.7 81 160.3 71.3 4.34 15.6 0.27 HFOC-254faE 26.0 74.0 1.813 10.0 69 159.3 70.7 4.20 12.6 0.22 HFOC-263ebEβγ 40.2 59.8 1.9 13 10.169 155.7 68.7 4.19 12.8 0.22 HFOC-272fbEβγ 19.0 81.0 2.4 17 12.4 85167.9 75.5 4.26 16.5 0.29 HFOC-494pcEβγ 36.3 63.7 0.8 6 5.3 37 140.860.4 4.08 6.1 0.11Data show the compositions of the present invention have evaporator andcondenser pressures similar to CFC-113. Some compositions also havehigher capacity or energy efficiency (COP) than CFC-113.

1. A refrigerant or heat transfer fluid composition selected from thegroup consisting of: C₄F₉OC₂H₅ and1-(difluoromethoxy)-1,2,2-trifluoroethane; C₄F₉OC₂H₅ and1-difluoromethoxy-2,2-difluoroethane; C₄F₉OC₂H₅ and2-methoxy-1,1,2-trifluoroethane; C₄F₉OC₂H₅ and1,1-difluoro-2-methoxyethane; and C₄F₉OC₂H₅ and1-(1,1,2,2-tetrafluoroethoxy)propane.
 2. A refrigerant or heat transferfluid composition suitable for use in refrigeration or air conditioningapparatus employing (i) centrifugal compressor, or (ii) multi-stagecentrifugal compressor, or (iii) a single slab/single pass heatexchanger, said composition comprising, said composition selected fromthe group consisting of; C₄F₉OC₂H₅ and1-(difluoromethoxy)-1,2,2-trifluoroethane; C₄F₉OC₂H₅ and1-difluoromethoxy-2,2-difluoroethane; C₄F₉OC₂H₅ and2-methoxy-1,1,2-trifluoroethane; C₄F₉OC₂H₅ and1,1-difluoro-2-methoxyethane; and C₄F₉OC₂H₅ and1-(1,1,2,2-tetrafluoroethoxy)propane.
 3. An azeotropic ornear-azeotropic composition selected from the group consisting of: about1 to about 62 weight percent C₄F₉OC₂H₅ and about 99 to about 38 weightpercent 1-(difluoromethoxy)-1,2,2-trifluoroethane; about 1 to about 67weight percent C₄F₉OC₂H₅ and about 99 to about 33 weight percent1-difluoromethoxy-2,2-difluoroethane; about 1 to about 76 weight percentC₄F₉OC₂H₅ and about 99 to about 24 weight percent2-methoxy-1,1,2-trifluoroethane; about 1 to about 67 weight percentC₄F₉OC₂H₅ and about 99 to about 33 weight percent1,1-difluoro-2-methoxyethane; and about 1 to about 99 weight percentC₄F₉OC₂H₅ and about 99 to about 1 weight percent1-(1,1,2,2-tetrafluoroethoxy)propane.
 4. An azeotropic compositionselected from the group consisting of: 11.9 weight percent C₄F₉OC₂H₅ and88.1 weight percent 1-(difluoromethoxy)-1,2,2-trifluoroethane having avapor pressure of about 14.7 psia (101 kPa) at a temperature of about52.7° C.; 26.0 weight percent C₄F₉OC₂H₅ and 74.0 weight percent1-difluoromethoxy-2,2-difluoroethane having a vapor pressure of about14.7 psia (101 kPa) at a temperature of about 54.0° C.; 40.2 weightpercent C₄F₉OC₂H₅ and 59.8 weight percent2-methoxy-1,1,2-trifluoroethane having a vapor pressure of about 14.7psia (101 kPa) at a temperature of about 54.0° C.; 19.0 weight percentC₄F₉OC₂H₅ and 81.0 weight percent 1,1-difluoro-2-methoxyethane having avapor pressure of about 14.7 psia (101 kPa) at a temperature of about48.1° C.; and 36.3 weight percent C₄F₉OC₂H₅ and 63.7 weight percent1-(1,1,2,2-tetrafluoroethoxy)propane having a vapor pressure of about14.7 psia (101 kPa) at a temperature of about 71.2° C.
 5. A process forproducing refrigeration, said process comprising evaporating thecomposition of claim 1, 2, 3, or 4, in the vicinity of a body to becooled, and thereafter condensing said composition.
 6. A process forproducing heat, said process comprising condensing the composition ofclaim 1, 2, 3, or 4 in the vicinity of a body to be heated, andthereafter evaporating said composition.
 7. A method of using thecompositions of claim 1, 2, 3, or 4, for heat transfer, said methodcomprising transferring said composition from a heat source to a heatsink.
 8. The composition of claim 1, further comprising at least oneultra-violet fluorescent dye selected from the group consisting ofnaphthalimides, perylenes, coumarins, anthracenes, phenanthracenes,xanthenes, thioxanthenes, naphthoxanthenes, fluoresceins, derivatives ofsaid dyes and combinations thereof.
 9. The composition of claim 2, 3, or4 further comprising at least one ultra-violet fluorescent dye selectedfrom the group consisting of naphthalimides, perylenes, coumarins,anthracenes, phenanthracenes, xanthenes, thioxanthenes,naphthoxanthenes, fluoresceins, derivatives of said dyes, andcombinations thereof.
 10. The composition of claim 8, further comprisingat least one solubilizing agent selected from the group consisting ofhydrocarbons, dimethylether, polyoxyalkylene glycol ethers, amides,ketones, nitriles, chlorocarbons, esters, lactones, aryl ethers,hydrofluoroethers, and 1,1,1-trifluoroalkanes; and wherein therefrigerant and solubilizing agent are not the same compound.
 11. Thecomposition of claim 10, wherein said solubilizing agent is selectedfrom the group consisting of: a) polyoxyalkylene glycol ethersrepresented by the formula R¹[(OR²)_(x)OR³]_(y), wherein: x is aninteger from 1 to 3; y is an integer from 1 to 4; R¹ is selected fromhydrogen and aliphatic hydrocarbon radicals having 1 to 6 carbon atomsand y bonding sites; R² is selected from aliphatic hydrocarbyleneradicals having from 2 to 4 carbon atoms; R³ is selected from hydrogen,and aliphatic and alicyclic hydrocarbon radicals having from 1 to 6carbon atoms; at least one of R¹ and R³ is selected from saidhydrocarbon radicals; and wherein said polyoxyalkylene glycol ethershave a molecular weight of from about 100 to about 300 atomic massunits; b) amides represented by the formulae R¹CONR²R³ andcyclo-[R⁴CON(R⁵)—], wherein R¹, R², R³ and R⁵ are independently selectedfrom aliphatic and alicyclic hydrocarbon radicals having from 1 to 12carbon atoms, and at most one aromatic radical having from 6 to 12carbon atoms; R⁴ is selected from aliphatic hydrocarbylene radicalshaving from 3 to 12 carbon atoms; and wherein said amides have amolecular weight of from about 100 to about 300 atomic mass units; c)ketones represented by the formula R¹COR², wherein R¹ and R² areindependently selected from aliphatic, alicyclic and aryl hydrocarbonradicals having from 1 to 12 carbon atoms, and wherein said ketones havea molecular weight of from about 70 to about 300 atomic mass units; d)nitriles represented by the formula R¹CN, wherein R¹ is selected fromaliphatic, alicyclic or aryl hydrocarbon radicals having from 5 to 12carbon atoms, and wherein said nitriles have a molecular weight of fromabout 90 to about 200 atomic mass units; e) chlorocarbons represented bythe formula RCl_(x), wherein; x is selected from the integers 1 or 2; Ris selected from aliphatic and alicyclic hydrocarbon radicals havingfrom 1 to 12 carbon atoms; and wherein said chlorocarbons have amolecular weight of from about 100 to about 200 atomic mass units; f)aryl ethers represented by the formula R¹OR², wherein: R¹ is selectedfrom aryl hydrocarbon radicals having from 6 to 12 carbon atoms; R² isselected from aliphatic hydrocarbon radicals having from 1 to 4 carbonatoms; and wherein said aryl ethers have a molecular weight of fromabout 100 to about 150 atomic mass units; g) 1,1,1-trifluoroalkanesrepresented by the formula CF₃R¹, wherein R¹ is selected from aliphaticand alicyclic hydrocarbon radicals having from about 5 to about 15carbon atoms; i) hydrofluoroethers represented by the formulaR¹OCF₂CF₂H, wherein R¹ is selected from aliphatic and alicyclichydrocarbon radicals having from about 5 to about 15 carbon atoms; andj) lactones represented by structures [B], [C], and [D]:

 wherein, R₁ through R₈ are independently selected from hydrogen,linear, branched, cyclic, bicyclic, saturated and unsaturatedhydrocarbyl radicals; and the molecular weight is from about 100 toabout 300 atomic mass units; and k) esters represented by the generalformula R¹CO₂R², wherein R¹ and R² are independently selected fromlinear and cyclic, saturated and unsaturated, alkyl and aryl radicals;and wherein said esters have a molecular weight of from about 80 toabout 550 atomic mass units.
 12. A method for using the composition ofclaim 10, said method comprising: introducing the composition into acompression refrigeration or air conditioning apparatus by (i)dissolving the ultraviolet fluorescent dye in the refrigerantcomposition of heat transfer fluid in the presence of the solubilizingagent, and introducing the combination into said compressionrefrigeration or air conditioning apparatus or (ii), combiningsolubilizing agent and and UV flurorescent dye and introducing saidcombination into refrigeration or air conditioning apparatus containingrefrigerant and/or heat transfer fluid.
 13. A method for using thecomposition of claim 8 or 10 in a compression refrigeration or airconditioning apparatus, said method comprising providing saidcomposition to said apparatus, and providing a suitable means fordetecting said composition at a leak point or in the vicinity of saidapparatus.
 14. A method of using the composition of claim 8 or 10, saidmethod comprising: (i) producing refrigeration by evaporating saidcomposition in the vicinity of a body to be cooled and thereaftercondensing said composition; or (ii) producing heat by condensing saidcomposition in the vicinity of the body to be heated and thereafterevaporation said composition.
 15. The composition of claim 1, 2, 3 or 4further comprising a thermal stabilizer or odor masking agent.
 16. Thecomposition of claim 15 wherein said thermal stabilizer is nitromethane.17. A method of using the composition of claim 3, wherein said methodcomprises, producing heat or refrigeration in a refrigeration or airconditioning system employing a multi-stage centrifugal compressor. 18.The method of claim 17 wherein said multi-stage compressor is atwo-stage centrifugal compressor.